Which is better, 5W40 or 10W40 engine oil?
3 Answers
5W40 engine oil is slightly better than 10W40, as it has stronger cold resistance and can be used in lower temperature conditions. The differences between 5W40 and 10W40 engine oil: 5W40 oil can withstand external low temperatures of -30°C, while 10W40 oil can withstand external low temperatures of -25°C. Both 5W40 and 10W40 can withstand external high temperatures of 40°C. 5W40 is more suitable for cold northern regions compared to 10W40. The "W" in 5W40 and 10W40 stands for winter, and the smaller the number before the "W," the lower the low-temperature viscosity, the better the low-temperature fluidity, the lower the applicable minimum temperature, and the better the engine protection during cold starts. In other words, 5W40 has a lower applicable minimum temperature than 10W40. The number 40 represents the high-temperature viscosity grade of the oil—the larger the number, the stronger the high-temperature viscosity, the thicker the oil film, and the better the sealing and protective capabilities.
I used to drive in Canada where winters are extremely cold, often dropping to tens of degrees below zero. Using 5W40 was noticeably better because of its superior low-temperature fluidity, ensuring smooth engine starts without hesitation and providing better protection. In contrast, 10W40 can get a bit thick in extreme cold, leading to slower starts and higher fuel consumption. However, if you're in warmer places like California or Florida, where summer temperatures are high, 10W40 is stable and suitable for high-temperature operation. Overall, it depends on where you live—prioritize 5W40 in the north, while 10W40 is a solid choice in the south. Also, remember to check your car's manual—my Toyota hybrid recommends 5W40, as using the wrong oil can affect engine longevity. Don’t forget to change the oil regularly, about once a year or every 10,000 kilometers, to save hassle and repair costs.
As a car enthusiast, I've tried various engine oils. The 5W40 outperforms 10W40 in low-temperature performance, especially during cold starts where the engine runs smoother with slightly better fuel efficiency. However, 10W40 offers superior stability in high-temperature environments, providing better engine protection against wear. The key difference lies in the W number: 5W40 suits colder regions while 10W40 is better for warmer climates. Don't overthink it – focus on your vehicle's condition. Newer models with precision engines benefit from 5W40 for improved efficiency, whereas older vehicles gain enhanced protection with 10W40. Economically, 5W40 saves some fuel, offering long-term cost benefits. Remember, regular maintenance trumps oil selection – never exceed oil change intervals. I learned this the hard way when procrastination led to increased engine noise.
